Microcosms constructed with stream sediments and radio-labeled chemicals are used to conduct biodegradation experiments. This gas chromatograph with a radiation detector is used to detect and identify reaction products created by the biodegradation of the radio-labeled chemicals
(Click on image for larger version)

Anthropogenic compounds, such as human hormones, human and veterinary antibiotics, and disinfectants, are being delivered to streams and rivers from wastewater treatment plants (WWTPs) throughout the United States. The environmental significance, including potentially harmful effects to humans and wildlife, is a topic of intense investigation. One aspect of this issue is to understand the persistence of these compounds in aquatic environments, including understanding the environmental conditions that lead to their degradation or persistence. U.S. Geological Survey (USGS) scientists are conducting research to document the potential for biodegradation of several emerging contaminant chemicals, such as caffeine, hormones, antibiotics, antimicrobial disinfectants, and other chemicals found in the effluent discharged from WWTPs. The scientists are conducting laboratory biodegradation experiments using microcosms constructed with stream sediments collected upstream and downstream of wastewater treatment plant outfalls. Radiolabled compounds are used in the microcosms so the scientists can attribute observed reaction products to the degradation of the compounds.

Samples withdrawn from each of the microcosms (septated serum vials) are injected with a syringe into a gas chromatograph for analysis. The microcosms are constructed with sediments collected upstream and downstream of wastewater treatment plant outfalls
(Click on image for larger version)